The Boston Bruins defense was a near impenetrable fortress in their sweep of the top-seeded Pittsburgh Penguins in the Eastern Conference Final. It allowed just two goals in four games to the most high-powered offense in the NHL.

Going into Wendesday's Game 1 of the 2013 Stanley Cup Final, many people expected the Bruins to maintain their impressive defensive play against the Chicago Blackhawks in the first Original Six final since 1979.

Instead, the Blackhawks earned a 4-3 triple-overtime victory to take the series opener in thrilling fashion.

The key to Chicago's success offensively was an aggressive forecheck and speed through the neutral zone. Boston does not have a mobile defense and lacks an elite puck-moving player on the blue line. This makes a strong forecheck an effective way to frustrate the Bruins in their own zone, force turnovers and create sustained attacking zone pressure.

The Blackhawks forecheck wore the Bruins down physically over the course of 110-plus minutes of intense playoff hockey. This was evident on Brandon Saad's goal in the second period to get Chicago on the board after falling behind 2-0.

It was the rookie forward's first career playoff goal, but it wouldn't have happened without a strong forecheck that resulted in a turnover. As the replay below shows, Marian Hossa goes around the net on the forecheck and wins a puck battle against Nathan Horton, then finds Saad in the slot for a quality scoring chance.

Another way that Chicago broke through the Bruins defense was the play of their bottom two lines, who won the majority of the puck battles along the boards and created traffic in front of Boston goaltender Tuukka Rask.

"They had a lot of energy shifts," said Blackhawks head coach Joel Quenneville when assessing his fourth line's performance in Game 1. "Seems like they would always start in our end, end in the other team's end. They haven't been together in a while, but it was like they played all year together today."

To no one's surprise, the two team's top-six forwards basically cancelled each other out, which made the performance of the bottom two lines on both sides very important to the outcome of the game. Chicago's bottom-six forwards outplayed their Boston counterparts throughout regulation and for most of the overtimes, and this proved to be the difference in Game 1.

The Blackhawks benefited from the speed and energy that their third and fourth lines provided the team in the second, third and overtime periods on Wednesday. They were able to roll all four lines consistently in the later stages of the game, which gave them an advantage over a fatigued Boston team missing depth because of Nathan Horton's injury.

Boston's bottom-six tallied a single point (a Tyler Seguin assist on the power play), while Chicago received five points from its third and fourth lines.

Inexplicably, the Penguins did not establish a net-front presence at the top the crease in the conference finals, which allowed Rask to get a good look at the puck and stop 134 of the 136 shots he faced in the series.

As expected, the Blackhawks put traffic in front of Rask on a consistent basis and were able to capitalize on deflections and screens, including on Shaw's game-winning goal.

"We've preached it: go to the net, you'll find a way to get a greasy goal," said Shaw in his postgame presser. "We did a heck of a job of it there in the third overtime."

Chicago rarely gets the credit it deserves for being a gritty team. The Blackhawks are loaded with elite, highly-skilled forwards such as Jonathan Toews, Marian Hossa and Patrick Kane, but they are capable of playing a heavy game with the Bruins and finding success.

When you combine its impressive amount of size and strength with a high level of overall team speed, it's easy to see why Chicago has the personnel to break down the Bruins defense in a seven-game series.

The game plan for Game 2 should include the team's three strengths from the series opener, which were an aggressive forecheck, getting traffic in front of Rask and outplaying Boston's bottom two lines.

Nicholas Goss is an NHL Lead Writer at Bleacher Report. Nick was a credentialed reporter at the 2011 Stanley Cup Final and 2012 NHL playoffs, and he will also be a credentialed writer at the 2013 Stanley Cup Final in Boston. All quotes obtained first hand or from NHL media notes.